Mass production of ophthalmic lenses, in particular hard or soft contact lenses, is usually performed in a fully automated manufacturing process. In an embodiment of such fully automated mass production the contact lenses are manufactured with reusable casting molds comprising male and female mold halves. The female mold halves are filled with a lens-forming material and the casting molds are subsequently closed with the corresponding male mold halves. Suitable lens-forming materials include but are not limited to polymers or pre-polymers based on polyvinyl alcohols (PVA) or silicone hydrogels (SiHy) as well as materials based on polyethylene glycols (PEG). The lens-forming material within the casting molds is then polymerized and/or cross-linked by irradiation with ultraviolet radiation. After polymerization and/or cross-linking the molds are opened and the formed contact lenses are removed from the male or female mold halves and transported to subsequent processing stations.
The male and female mold halves of reusable casting molds are provided with lens-forming surfaces which are typically made from highly finished glass, for example quartz glass. Lens-forming surfaces which are made of glass or quartz glass are durable regarding exposure to UV-light and organic solvents. They are reliably cleanable, resistant to abrasion, and therefore suitable for multiple use in the mass production of ophthalmic lenses.
In order to meet the needs of the users, large numbers of contact lenses with different parameters must be produced, in particular as regards contact lenses for single use only. Such parameters include but are not limited to the refraction power of a contact lens, the base curve, the toric shape of the lens, etc. Thus, for the manufacture of all types of contact lenses a large number of different casting molds is required and must be held on stock. Considerable care must be taken in the logistics and handling of the casting molds in order to avoid a mix-up of casting molds as they are prepared for use in the fully automated manufacturing process. Typically, in preparation of production a plurality of such casting molds are mounted to a mold carrier which is then placed on the manufacturing line. Since casting molds having different parameters may be mounted to the same mold carrier at different locations on the mold carrier, it is essential that the individual casting molds having the desired parameters are mounted to the mold carrier at the intended positions on the mold carrier before the mold carrier is placed on the manufacturing line so as to avoid production of contact lenses having parameters different from those originally intended.
Therefore, one object of the invention is to facilitate the logistics and handling of a large number of casting molds with different parameters and to avoid mix-up of casting molds as they are prepared for use in the fully automated manufacturing process. In addition, it is desirable to allow for an automated verification of the casting molds even after they have been placed on the manufacturing line.